Multiple-break switch



Dec. 16, 1930. H. J. HAMMERLY MULTIPLE BREAK SWITCH 2 Sheets-Sheet 1 Filed Jan. 15, 1950 Dec. 16, 19300 H. J. HAMMERLY 'MULTIPLE BREAK SWIT Filed Jan.

15, 1930 2 Sheets-Sheet 2 INVENTOR Patented Dec. 16, 1930 -UNITED STATES PATENT OFFICE CORPORATION HERMAN J. HAMMERLY, or WALLINGFORD, CONNECTICUT, Assrenon TO THE 'rnum- BULL ELECTRIC MANUFACTURING COM PANY, 0F PLAINVILLE, CONNECTICUT, A

MULTIPLE-BREAK SWITCH Application filed January 15, 1930. Serial No. 420,927.

My present invention applies particularly to electric switches of the safety type such, for instance, as is shown in the Getchell Patent #1534515, April 21, 1925 and an improvement over the details of former constructions such as are disclosed for instance by the Getchell Patents #1,57 0,237 January 19, 1926, and #1,600,167 September 14, 1926.

At the present time, electrical devices, particularly switches, have come into such common or general use, that the underwriters and insurance companies are very much more rigid and strict in their safety requirements applying to all such devices and in the more recent and more severe tests it has been found, for instance, that electric switches which successfully withstood the former preliminary tests do not meet the requirements of the present day standard tests. Many switches which were cdnsidered perfectly safe a year ago now fail to pass the more rigid testing requirements and are therefore considered as not safe and, of course, cannot be approved by the underwriters.

One of the principal Causes of trouble in switches of this type, particularly of the enclosed type, is the arcing which occurs'between the stationary and movable contacts in the circuit opening movement of the switch. The first arcing that occurs between the respective contacts leaves its mark which may be in the formof simply blackened or smoked contacts or the contact surfaces may be pitted, or burned away but whatever the effect of the first arcing may be, each successive arcing will be progressively more severe until the contacts actually burn up or are welded 'together.

My present invention is directed to the improvement of the contacts of: switches particularly of the knife blade type. Obviously, a double-break switch will have far less tendency to are than a single'break switch and, of course, a switch having four circuit breaking points in each pole or leg of the circuit, will have a safety factor which is tremendously greater than. that of a double-break switch.

One object of my invention is to provide a form of blade construction which, in its nor? mal" operation, will cause four successive in the on vided with a single solid blade such as is shown in two of the forementioned Getchell patents.

Another object is to provide a switch blade made in two separate parts, insulated-from each other and so mounted that when the switch is operated, the pair of blade members will engage with or disengage from the corelated stationary contacts so as to cause tour successive makes or breaks in the circuit and so that when the two blades are position they,will'function as a single blade.

Another object is to provide a switch member the parts of which can be readily made and assembled.

In the form shown the switch has two oppositely disposed stationary switch contacts and an intervening insulating cylinder carrying two parallel blades for each pair of contacts. This cylinder is made up of sections which are grooved and ribbed on their adjacent ends to receive the blades.

Obviously the principle involved may be incorporated in switch blades of other forms.

Fig. 1' is a perspective view of parts of a switch embodying one form of my invention, the parts being in the open circuit position.

Fig. 2 is a transverse sectional view of the same the parts being in the closed circuit position. v I

Fig. 3 is an end view showing the parts in position as the circuit is being opened.

Fig. 4 is side view and section of the movable switch member.

Fig. 5 is a perspective view of one of the sections of the switch member and the parts- The switch may have any number of Cir cuit controlling units. In the drawing we have shown the usual two unit type adapted 10c to break both branches of a circuit. Each unit has suitable contact jaws 8 and 9 secured to the base in any suitable manner, as for instance, by means of screws 10 and 11 and each stationary contact is provided with a circuit terminal such as 12 and 13.

The movable switch member is in the form of a rotatable or oscillating cylinder which carries the switch blades for reacting with the respective stationary contact jaws. Preferably this cylinder is formed of a number of separately made parts such as 14:, 15 and 16 which may be of suitable molded insulating composition. This cylinder has end plates 17 and 18 and the parts are held together by rivets or tie-rods l919. The end platesare provided with projecting shaft or spindle portions 2021 which in turn are supported in suitable bearings in the brackets such as 22, which are suitably supported on the base 7. One of the end plates is provided with a projecting pin or crank arm 23 by means of which the movable switch member is operated. Such switches are also preferably provided with suitable snap action mechanism such for instance as that shown in the Getchell Patent 1,534,515.

The conductin member or blade of each switch unit cons1sts of two strips or bars such as 2424 the opposite ends of which are adapted to coact with the respective stationary contact jaws 8 and 9. These bars are loosely supported in grooves or passages extending through the lnsulating drum or tudinal movement with respect to the C31.

carrier. The bars are prevented from longirier by suitable grooves and projections on the corresponding parts, as for instance, the notches 25 in the inner edges of the bars 24: which fit loosely over the opposite sides of a projection 26 on the cylinder part 14;. The cylinder part 16 is provided with a recess 27 for the end of the projection 26 to assist in holding the parts in their proper relative positions.

The grooves or passages in the insulating carrier are preferably formed by projections such as 28 and 29 on the part 14 and the projection 80 on the part 16 which projections leave grooves such as 31 in the central part 14 and'the groove 32 between the parts 14 and 16. The relative sizes of the projections and grooves with respect to the conducting bars 2424 is such as to hold the bars in v their proper positions and yet allow them to tilt slightly so as.- to ensure flat cont-act with the stationary contact jaws even though the parts may be slightly out of position or slightly bent as sometimes occurs. In other words, the important feature is perfection of contact between the movable switch blades and the stationary contacts rather than rigidthree sections as above mentioned and the switch blades for each unit will be supported in a similar manner to that above mentioned. For this purpose the opposite ends of the part 14 are similar but reversed in position. VJhere one end has the rib or projection 29, the other end has a corresponding rib or projection 29. This latter end has a projection 28 corresponding to the portion cut away to form the groove 32.

In the closed'circuit position as shown in Fig. 2, it will be seen that current flows through both of the bars 24 the ends of which engage the respective stationary contacts 8 and 9. When the circuit is open the parts occupy the same position shown in Fig. l, the base having a groove 33 for the end of the contact plate. As the circuit is being opened it will be seen that the ends of the parts of the blades leave the stationary contacts successively so as to divide the circuit breaking action into a number of parts thus decreasing the arcing efi'ect and tending to distribute the arcing points and reduce the wear and tear on the switch.

I claim:

1. In a double break switch unit the combination of oppositely disposed stationary contacts, an insulating carrier mounted between the contacts and a switch blade carried by the carrier and consisting of two separately movable conducting bars having their ends projecting from opposite sides of the carrier.

2. In an electric switch, an insulating carrier composed of at least two parts having parallel grooves arranged in adjacent faces of the parts and a blade member consisting of two separate bars loosely mounted in said grooves.

3. In a switch, a pair of stationary jaws, a rotatable switch member mounted between the jaws and having a divided blade whose ends successively engage and-disengage the jaws as the switch is closed and opened.

4. A switch init comprising a carrier having insulating sections with grooves in adjacent faces and a projection on one extending into the other a pair'of blade members in the grooves having notches fitting the projection to prevent longitudinal movement the blade inembers in the carrier.

5. In a switch unit the combination of oppositely disposed stationary contacts, an insulating carrier mounted between the contacts and a switch blade carried by the carrier and consisting of two conducting bars having their ends projecting from opposite sides of the carrier and means for interlocking he bars with the central part of the carrier.

6. In an electric switch, an insulating car rier composed of at least two parts having parallel grooves and an interfitting projection and recess arranged in adjacent faces IOU ' of the'parts and a blade member consistin of two separate bars loosely mounted in sai grooves and interlocked with said projection.

7. In a switch, a, pair of stationery jaws, a'rotatable switch member mounted between the jaws and having a divided blade whose. ends successively engage and disengage the Laws as the switch is closed and oFened said lade and member begin a centre. interlock.

HERMAN HAMMERLY 

